Process for making (2S, 3S, 5S) oxetanone derivatives

ABSTRACT

This invention relates to novel processes for making (2S, 3S, 5S) oxetanone derivative lipase inhibitor compounds and intermediates therefor, which processes for producing such derivatives that are useful as lipase inhibitors are capable of being scaled to commercial quantities. Further the invention relates to processes for producing salts and for producing pharmaceutical compositions compounds comprising at least one such oxetanone derivative or salt, as well as methods for using such compounds and compositions for inhibiting lipases.

FIELD OF THE INVENTION

[0001] This invention relates to novel oxetanone derivative compoundsand processes for producing such derivatives which are useful as lipaseinhibitors. Further the invention relates to processes for producingsalts and for producing pharmaceutical compositions compounds comprisingat least one such oxetanone derivative or salt, as well as methods forusing such compounds and compositions for inhibiting lipases. In oneaspect the invention relates to lipase inhibitors which include on thesame molecule an oxetanone derivative portion capable of inhibiting alipase and a non-absorbable moiety such a polysaccharide, which arecovalently linked or are in the form of a salt. In a preferred aspect ofthe invention the non-absorbable moiety is lipophilic and will associatewith oils or fats. An absorbable oxetanone lipase inhibitor may berendered non-absorbable by covalent linking it directly or indirectly toa non-absorbable moiety and thereby producing a novel non-absorbablelipase inhibitor.

BACKGROUND OF THE INVENTION

[0002] Some lipase-inhibiting oxetanones and intermediates for makingthem are well known. See for example, U.S. Pat. Nos. 5,931,463,5,175,186, 4,189,438 and 4,202,824. However, there is a need forimproved processes for making oxetanones in commercial quantities thatare have low toxicity and are essentially not absorbable by thedigestive system of mammals such as dogs, cats, non-human primates andhuman primates.

[0003] Lipase inhibitors such as esterastin (2S, 3S, 5S)3,5-hydroxy-2-hexadeca-7,10-dienoic 1,3-lactone), tetrahydroesterastin(2S, 3S, 5S) 3,5-di-hydroxy-2-hexylhexadecanoic 1,3-lactone, and thelike (see U.S. Pat. No. 4,189,438), are well-known as lipase inhibitorsand are useful as pancreatic cholesterol esterase inhibitors. Whilethese lipase inhibitor can be obtained by cultivating microbes asdescribed in U.S. Pat. No. 4,189,438, it is believed that examples ofsuccessful synthetic procedures for effectively making such compounds incommercially acceptable quantities from intermediates other than thoseobtained from microbes have not been described in the literature.

[0004] Further, esterastin and tetrahydroesterastin are excluded byproviso from the claims of the U.S. Pat. No. 5,175,186, which relates toa synthetic method for making certain analogs of esterastin andtetrahydroesteratin. The specification of that document does notillustrate the direct production of esterastin or tetrahydroesteratin orother (5S) analogs before the 2S, 3S oxetanone (lactone) ring structureis formed. Further page 6, lines 21-44, of the U.S. Pat. No. 5,175,186points to an asymetrical hydrogenation synthesis step, which makesobtaining (2S, 3S, 5S) analog compounds before the direct closure of theoxetanone ring problematic. On page 6, when an intermediate compoundhaving the 5 hydroxyl group in the R configuration (6R intermediate), isselectively hydrogenated only the (3S, 4S, 6R) intermediates result,which convert to a final compound having a 2S, 3S, 5R configuration.Likewise, when a only a 6S intermediate is used the (3R, 4R, 6S)hydrogenation intermediates result. The U.S. Pat. No. 5,175,186 does notillustrate a feasible and efficient solution for resolving such asynthetic difficulty prior to closure of the oxetanone ring.

[0005] Accordingly, there is a need in the art for an improvedcommercial process for efficiently making tetrahydroesterastin and its(2S, 3S, 5S) analogs in a enantiomeric excess of greater than 70% by theuse of 2S, 3S, 5S intermediate compounds which are formed prior to theformation of the oxetanone ring structure.

SUMMARY OF THE INVENTION

[0006] In one aspect the present invention relates to novel process formaking in at least 70% enantiomeric purity a (3S, 4S, 6S) oxetanonecompound of the formula (I),:

[0007] or a salt thereof

[0008] wherein:

[0009] R¹ and R³ are each independently a C₁ to C₁₈ straight or branchedalkyl hydrocarbon chain, and

[0010] R₂ is hydrogen or an alcohol protecting group R₁₀, wherein R₁₀can be replaced by a hydrogen atom via ester hydrolysis or hydrogenationether degradation, comprising the steps of:

[0011] (a) selectively hydrogenating a composition comprising a compoundwhich is a member selected from the group consisting of (6R)tetrahydro-2H-pyran-2-one compound of formula (II) and (6R)5,6-dihydro-2H-pyran-2,4-dione of formula (IIa):

[0012] wherein

[0013] R⁵ is hydrogen or an alcohol protecting group, which can bereplaced by a hydrogen atom via hydrogenation, and R¹ and R³ are definedas in formula (I), by hydrogenating the compound of formula II with ahydrogenation catalyst selected from the group consisting of PtO₂, RaneyNichel and the like, and exchanging hydrogen atoms at the 3 and 4 ringpositions or oxidizing the 4-oxo group to provide a (3S, 4S, 6R)4-hydroxy-tetrahydro-2H-pyran-2-one compound of the formula (III):

[0014] wherein R¹ and R³ are defined as in formula (I);

[0015] (b) re-protecting the 4-hydroxy group of the compound of formula(II) produced in (a) with an ether protecting group R⁶, which can bereplaced by a hydrogen atom via ester hydrolysis or hydrogenation etherdegradation, opening the lactone ring and esterifying the resulting freeacid group to provide a (2S, 3S, 5R) [R⁷]2-[R³]-3-[R⁶⁻oxy]-5-[hydroxy,R¹] pentanoic acid ester compound of the formula (IV):

[0016] wherein

[0017] R¹ and R³ are defined as in formula (I),

[0018] R⁶ is an alcohol protecting group, which can be replaced by ahydrogen atom via ester hydrolysis or hydrogenation ether degradation,and

[0019] R⁷ is an ester group which can be removed by base or acidhydrolysis, or by hydrogenation;

[0020] (c) inverting the chirality of the 5-hydroxy group of thecompound of formula (IV) produced in step (b), wherein the inversioncomprises a step which is a member selected from the group consisting of

[0021] (i) a Mitsunobu reaction,

[0022] (ii) esterifying the 5-hydroxy group to a carboxylic acid estersuch as the trichloroacetic acid ester, and the like, and hydrolyzingthe resultant ester in a water ether solvent such as 3:1 H₂O/dioxane,and

[0023] (iii) esterifying the 5-hydroxy group to a sulfonic acid ester,such as p-toluene sulfonic acid ester and the like, and reacting theester with an excess of an organic acid salt selected from the groupconsising of potassium acetate, sodium acetate, tetraethylammoniumacetate, and the like, to provide an ester exchange with the organicacid,

[0024] wherein the free inverted (5S) 5-hydroxy group of (i) and (ii) isesterified with a hydroxy protecting group R¹⁰ which can be which can bereplaced by a hydrogen atom via ester hydrolysis or hydrogenation etherdegradation, to provide a compound of the formula (V):

[0025] wherein

[0026] R¹ and R³ are defined as in formula (I),

[0027] R⁶ is an alcohol protecting group, which can be replaced by ahydrogen atom via ester hydrolysis or hydrogenation ether degradation,

[0028] R⁹ is an ester group which can be removed by base or acidhydrolysis, or by hydrogenation, and

[0029] R¹⁰ is an alcohol protecting group, which can be replaced by ahydrogen atom via ester hydrolysis or hydrogenation ether degradation,and wherein R¹⁰ is selectively removable with respect to the R⁶ alcoholprotecting group; and

[0030] (d) selectively removing the R⁶ alcohol protecting group and R⁹ester group of the compound of formula (V) produced in (c), andcyclizing the 3 position alcohol group with the 1 position acid groupusing a lactone cyclizing catalyst, such as benzene-sulphonyl chloride,in a solvent such as pyridine at a temperature of about −10 to 10° C.and optionally replacing the R¹⁰ alcohol protecting group of formula (V)with a hydrogen atom, to yield a (3S, 4S, 6S) oxetanone compound of theformula (I):

[0031] or a salt thereof.

[0032] In a preferred aspect, the process provides a compound of formula(I) wherein R1 is undecyl, R³ is hexyl and R² is hydrogen, which is (2S,3S, 5S) tetrahydroesterastin.

[0033] In another aspect the present invention relates to coupling suchcompound of formula (I) to an acyl compound via an acid or baseesterification procedure without inversion of the 5S hydroxy group.

[0034] In another aspect the present invention provides a novelintermediate (2S, 3 S, 5 S) compound of the formula:

[0035] wherein:

[0036] R¹ and R³ are each independently a C₁ to C₁₈ straight or branchedalkyl hydrocarbon chain, and

[0037] R² is hydrogen or an alcohol protecting group R₁₀, wherein R¹⁰can be replaced by a hydrogen atom via ester hydrolysis or hydrogenationether degradation, and R¹⁰ is selectively removable with respect to theR⁶ alcohol protecting group,

[0038] R⁶ is an alcohol protecting group, which can be replaced by ahydrogen atom via ester hydrolysis or hydrogenation ether degradation,and

[0039] R⁹ is an ester group which can be removed by base or acidhydrolysis, or by hydrogenation, or, a salt thereof.

[0040] In a preferred aspect, the invention providessuch an intermediatecompound wherein R¹ is undecyl or heptadecyl and R³ is ethyl or hexyl,or a salt thereof.

DETAILED DESCRIPTION OF THE INVENTION

[0041] Definitions

[0042] In accordance with the present invention and as used herein, thefollowing terms are defined with the following meanings, unlessexplicitly stated otherwise.

[0043] The term “alkenyl” refers to a trivalent straight chain orbranched chain unsaturated aliphatic radical. The term “alkinyl” (or“alkynyl”) refers to a straight or branched chain aliphatic radical thatincludes at least two carbons joined by a triple bond. If no number ofcarbons is specified alkenyl and alkinyl each refer to radicals havingfrom 2-12 carbon atoms.

[0044] The term “alkyl” refers to saturated aliphatic groups includingstraight-chain, branched-chain and cyclic groups having the number ofcarbon atoms specified, or if no number is specified, having up to 12carbon atoms. The term “cycloalkyl” as used herein refers to a mono-,bi-, or tricyclic aliphatic ring having 3 to 14 carbon atoms andpreferably 3 to 7 carbon atoms.

[0045] As used herein, the terms “carbocyclic ring structure” and “C₃₋₁₆carbocyclic mono, bicyclic or tricyclic ring structure” or the like areeach intended to mean stable ring structures having only carbon atoms asring atoms wherein the ring structure is a substituted or unsubstitutedmember selected from the group consisting of: a stable monocyclic ringwhich is aromatic ring (“aryl”) having six ring atoms; a stablemonocyclic non-aromatic ring having from 3 to 7 ring atoms in the ring;a stable bicyclic ring structure having a total of from 7 to 12 ringatoms in the two rings wherein the bicyclic ring structure is selectedfrom the group consisting of ring structures in which both of the ringsare aromatic, ring structures in which one of the rings is aromatic andring structures in which both of the rings are non-aromatic; and astable tricyclic ring structure having a total of from 10 to 16 atoms inthe three rings wherein the tricyclic ring structure is selected fromthe group consisting of: ring structures in which three of the rings arearomatic, ring structures in which two of the rings are aromatic andring structures in which three of the rings are non-aromatic. In eachcase, the non-aromatic rings when present in the monocyclic, bicyclic ortricyclic ring structure may independently be saturated, partiallysaturated or fully saturated. Examples of such carbocyclic ringstructures include, but are not limited to, cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, adamantyl, cyclooctyl, [3.3.0]bicyclooctane,[4.3.0]bicyclononane, [4.4.0]bicyclodecane (decalin),2.2.2]bicyclooctane, fluorenyl, phenyl, naphthyl, indanyl, adamantyl, ortetrahydronaphthyl (tetralin). Moreover, the ring structures describedherein may be attached to one or more indicated pendant groups via anycarbon atom which results in a stable structure. The term “substituted”as used in conjunction with carbocyclic ring structures means thathydrogen atoms attached to the ring carbon atoms of ring structuresdescribed herein may be substituted by one or more of the substituentsindicated for that structure if such substitution(s) would result in astable compound.

[0046] The term “aryl” which is included with the term “carbocyclic ringstructure” refers to an unsubstituted or substituted aromatic ring,substituted with one, two or three substituents selected fromloweralkoxy, loweralkyl, loweralkylamino, hydroxy, halogen, cyano,hydroxyl, mercapto, nitro, thioalkoxy, carboxaldehyde, carboxyl,carboalkoxy and carboxamide, including but not limited to carbocyclicaryl, heterocyclic aryl, and biaryl groups and the like, all of whichmay be optionally substituted. Preferred aryl groups include phenyl,halophenyl, loweralkylphenyl, napthyl, biphenyl, phenanthrenyl andnaphthacenyl.

[0047] The term “arylalkyl” which is included with the term “carbocyclicaryl” refers to one, two, or three aryl groups having the number ofcarbon atoms designated, appended to an alkyl group having the number ofcarbon atoms designated. Suitable arylalkyl groups include, but are notlimited to, benzyl, picolyl, naphthylmethyl, phenethyl, benzyhydryl,trityl, and the like, all of which may be optionally substituted.

[0048] The terms “halo” or “halogen” as used herein refer to Cl, Br, For I substituents. The term “haloalkyl”, and the like, refer to analiphatic carbon radicals having at least one hydrogen atom replaced bya Cl, Br, F or I atom, including mixtures of different halo atoms.Trihaloalkyl includes trifluoromethyl and the like as preferredradicals, for example.

[0049] The term “methylene” refers to —CH₂—.

[0050] Preferred Embodiments

[0051] In one embodiment the present invention relates to novel processfor making in at least 70% enantiomeric purity a (3S, 4S, 6S) oxetanonecompound of the formula (I),:

[0052] or a salt thereof

[0053] wherein:

[0054] R¹ and R³are each independently a C₁ to C₁₈ straight or branchedalkyl hydrocarbon chain, and

[0055] R² is hydrogen or an alcohol protecting group R¹⁰, wherein R¹⁰can be replaced by a hydrogen atom via ester hydrolysis or hydrogenationether degradation, comprising the steps of:

[0056] (a) selectively hydrogenating a composition comprising a compoundwhich is a member selected from the group consisting of (6R)tetrahydro-2H-pyran-2-one compound of formula (II) and (6R)5,6-dihydro-2H-pyran-2,4-dione of formula (IIa):

[0057] wherein

[0058] R⁵ is hydrogen or an alcohol protecting group, which can bereplaced by a hydrogen atom via hydrogenation, and R¹ and R³ are definedas in formula (I), by hydrogenating the compound of formula II with ahydrogenation catalyst selected from the group consisting of PtO₂, RaneyNichel and the like, and exchanging hydrogen atoms at the 3 and 4 ringpositions or oxidizing the 4-oxo group to provide a (3S, 4S, 6R)4-hydroxy-tetrahydro-2H-pyran-2-one compound of the formula (III):

[0059] wherein R¹ and R³ are defined as in formula (I);

[0060] (b) re-protecting the 4-hydroxy group of the compound of formula(II) produced in (a) with an ether protecting group R⁶, which can bereplaced by a hydrogen atom via ester hydrolysis or hydrogenation etherdegradation, opening the lactone ring and esterifying the resulting freeacid group to provide a (2S, 3S, 5R)[R⁷]2-[R³]-3-[R⁶⁻oxy]-5-[hydroxy,R¹] pentanoic acid ester compound ofthe formula (IV):

[0061] wherein

[0062] R¹ and R³ are defined as in formula (I),

[0063] R⁶ is an alcohol protecting group, which can be replaced by ahydrogen atom via ester hydrolysis or hydrogenation ether degradation,and

[0064] R⁷ is an ester group which can be removed by base or acidhydrolysis, or by hydrogenation;

[0065] (c) inverting the chirality of the 5-hydroxy group of thecompound of formula (IV) produced in step (b), wherein the inversioncomprises a step which is a member selected from the group consisting of

[0066] (i) a Mitsunobu reaction,

[0067] (ii) esterifying the 5-hydroxy group to a carboxylic acid estersuch as the trichloroacetic acid ester, and the like, and hydrolyzingthe resultant ester in a water ether solvent such as 3:1 H₂O/dioxane,and

[0068] (iii) esterifying the 5-hydroxy group to a sulfonic acid ester,such as p-toluene sulfonic acid ester and the like, and reacting theester with an excess of an organic acid salt selected from the groupconsising of potassium acetate, sodium acetate, tetraethylammoniumacetate, and the like, to provide an ester exchange with the organicacid,

[0069] wherein the free inverted (5S) 5-hydroxy group of (i) and (ii) isesterified with a hydroxy protecting group R¹⁰ which can be which can bereplaced by a hydrogen atom via ester hydrolysis or hydrogenation etherdegradation, to provide a compound of the formula (V):

[0070] wherein

[0071] R¹ and R³ are defined as in formula (I),

[0072] R⁶ is an alcohol protecting group, which can be replaced by ahydrogen atom via ester hydrolysis or hydrogenation ether degradation,

[0073] R⁹ is an ester group which can be removed by base or acidhydrolysis, or by hydrogenation, and

[0074] R¹⁰ is an alcohol protecting group, which can be replaced by ahydrogen atom via ester hydrolysis or hydrogenation ether degradation,and wherein R¹⁰ is selectively removable with respect to the R⁶ alcoholprotecting group; and

[0075] (d) selectively removing the R⁶ alcohol protecting group and R⁹ester group of the compound of formula (V) produced in (c), andcyclizing the 3 position alcohol group with the 1 position acid groupusing a lactone cyclizing catalyst, such as benzene-sulphonyl chloride,in a solvent such as pyridine at a temperature of about −10 to 10° C.and optionally replacing the R¹⁰ alcohol protecting group of formula (V)with a hydrogen atom, to yield a (3S, 4S, 6S) oxetanone compound of theformula (I):

[0076] or a salt thereof.

[0077] In a preferred aspect, the process provides a compound of formula(I) wherein R1 is undecyl, R³ is hexyl and R² is hydrogen, which is (2S,3S, 5S) tetrahydroesterastin.

[0078] In another aspect the present invention relates to coupling suchcompound of formula (I) to an acyl compound via an acid or baseesterification procedure without inversion of the 5S hydroxy group.

[0079] In another aspect the present invention provides a novelintermediate (2S, 3S, 5S) compound of the formula:

[0080] wherein:

[0081] R¹ and R³ are each independently a C₁ to C₁₈ straight or branchedalkyl hydrocarbon chain, and

[0082] R² is hydrogen or an alcohol protecting group R₁₀, wherein R¹⁰can be replaced by a hydrogen atom via ester hydrolysis or hydrogenationether degradation, and R¹⁰ is selectively removable with respect to theR⁶ alcohol protecting group,

[0083] R⁶ is an alcohol protecting group, which can be replaced by ahydrogen atom via ester hydrolysis or hydrogenation ether degradation,and

[0084] R⁹ is an ester group which can be removed by base or acidhydrolysis, or by hydrogenation, or, a salt thereof.

[0085] In a preferred aspect, the invention provide such intermediatecompounds wherein R¹ is undecyl or heptadecyl and R³ is ethyl or hexyl,or a salt thereof.

[0086] In a preferred aspect the above process comprises making a (3S,4S, 6S) oxetanone compound of the formula (I), or a salt thereof, in atleast 90% enantiomeric purity:

[0087] In another preferred aspect the present invention provides aprocess for making a compound wherein R¹ is undecyl or heptadecyl and R³is ethyl or hexyl in at least 90% enantiomeric purity:

[0088] In one aspect the invention provides a process wherein thecompound of formula (II) in step (a) is present at a ratio of from 90 to100% with respect to the corresponding (6S) enantiomer, and comprisesthe step of isolating such a compound of formula (II) in an enantiomericexcess of from 90 to 100% with respect to the corresponding (6S)enantiomer.

[0089] In a preferred aspect the invention provides a process whereinthe compound of formula (II) in step (a) is present at a ratio ofgreater than 97% with respect to the corresponding (6S) enantiomer, andcomprises the step of isolating such a compound of formula (II) in anenantiomeric excess of greater than 97% with respect to thecorresponding (6S) enantiomer.

[0090] The present invention provides a process as described above,which further comprises isolating a compound which is a member selectedfrom the group consisting of the 6R compound of formula (IV), or itscorresponding (6R, 3RS, 4RS) racemate with an alcohol protected 3hydroxyl group, from a compound which is a member selected from the 6S,3R, 4R enantiomer with an alcohol protected 3 hydroxyl groupcorresponding to the compound in formula (IV) and a compound which isthe (6S, 3RS, 4RS) racemate corresponding to the compound of formula(IV), comprising a separation step with is a member selected from thegroup consisting of:

[0091] (i) selectively esterifying the 6-position hydroxyl group in thepresence of a lipase such as PS 30, porcine pancreas lipase, and thelike, and separating the ester from the alcohol,

[0092] (ii) selectively hydrolyzing an ester an ester of the 6-positionhydroxyl group via a lipase such as PS 30, porcine pancreas lipase, andthe like, and separating the ester from the alcohol,

[0093] (iii) forming a chiral salt with a chiral alcohol resolving agentsuch as L-alaninol, D-alaninol, L-tartaric acid, D-tartaric acid,S-methylbenzyl-amine, D-methylbenzylamine in an appropriate solvent suchas methyl acetate, and the like, and separating the two enantiomers byre-cyrstallization; and

[0094] (iv) other known chiral alcohol separating procedures,

[0095] and removing any ester or protecting groups from the 6R chiralhydroxyl group.

[0096] In another preferred aspect, the present invention provides sucha process which further comprises the steps of

[0097] (a) inverting the 5S hydroxyl group of a (2R, 3R, 5S or 2RS, 3RS,5S) [R⁷]2-[R³]-3-[R⁶⁻oxy]-5-[hydroxy, R¹] pentanoic acid ester compoundof the formula (VII):

[0098] wherein

[0099] R¹, R³, R⁶ and R⁷ are defined as in formula IV;

[0100] wherein the inversion comprises a step which is a member selectedfrom the group consisting of

[0101] (i) a Mitsunobu reaction, and freeing the hydroxyl group

[0102] (ii) esterifying the 5-hydroxy group to a carboxylic acid estersuch as the trichloroacetic acid ester, and the like, and hydrolyzingthe resultant ester in a water ether solvent such as 3:1 H₂O/dioxane tothe inverted hydroxyl group,

[0103] (iii) esterifying the 5-hydroxy group to a sulfonic acid ester,such as p-toluene sulfonic acid ester and the like, and reacting theester with an excess of an organic acid salt selected from the groupconsising of potassium acetate, sodium acetate, tetraethylammoniumacetate, and the like, to provide an ester exchange with the organicacid, and hydrolyzing the organic acid ester to the inverted hydroxylgroup,

[0104] (iv) other known chiral alcohol inversion procedures,

[0105] (b) hydrolyzing the R⁷ ester group to provide the free acidcompound of the formula (VIII):

[0106] wherein

[0107] R¹, R³ and R⁶ and R⁷ are defined as in formula (VII), and

[0108] (c) cyclizing the inverted alcohol group of the compound offormula (VIII) with the 1 position acid group in the presence of alactone cyclizing catalyst such as tonuene-4-sulfonic acid monohydratein an alcohol at about 50-60° C. to provide a 6Rtetrahydro-2H-pyran-2-one compound of formula (IX):

[0109] wherein

[0110] R¹, R³, R⁶ and R⁷ are defined as in formula (VIII); and

[0111] (d) selectively hydrogenating the (6R) tetrahydro-2H-pyran-2-onecompound of formula (IX) with a hydrogenation catalyst selected from thegroup consisting Of PtO₂, Raney Nichel and the like, and exchanginghydrogen atoms at the 3 and 4 ring positions to provide a (3S, 4S, 6R)4-hydroxy-tetrahydro-2H-pyran-2-one compound of the formula (IV):

[0112] wherein R¹ and R³ are defined as in formula (I).

[0113] The intermediate compounds of formulae (II) and (IV) can beefficiently made from commercially feasible materials by adaptingseveral methods known in the art and by refining the synthesis to avoidunnecessary or costly steps. Further, the following non-limitingreaction schemes, some steps of which are novel, are merely to exemplifythe invention.

[0114] A process for making an intermediate compound for synthesizing acompound of the formula:

[0115] comprising the steps of:

[0116] treating dodecyl aldehyde (lauraldehyde) with a saturated aqueoussolution of a bisufite such as sodium bisulfite to form a bisulfite saltof the formula:

[0117] (b) reacting the bisulfite salt with a 2-haloacetic acid R ester,such as 2 bromoacetic acid ethyl ester in a suitable solvent such as THFand water and in the presence of a catalytic amount of an acid such asHCl to produce a ketone derivative of the formula:

[0118] (c) reducing the ketone derivative with NaBH₄, or the like, andoptionally resolving the R and S enantiomer by forming an ester underchiral resolving conditions, such as esterifying the alcohol in thepresence of the pseudomonas lipase PS 30 and the like, or by reducingthe ketone carbonyl group with a chiral hydrogenation catalyst, at atemperature from 0° C. to 50° C. preferably at room temperature, in asuitable solvent, such as ethanol and the like, or reducing the ketonegroup with a chiral borane such as DIP—Cl (Aldrich) and protecting thealcohol with a protecting group (P1), such as t-butyldimethylsilyl byreaction with t-butyldimethylchlorosilane in dimethylformamide (DMF), toprovide a compound of the formula:

[0119] (d) reacting the protected alcohol with at least one equivalentof a base such as NaOH followed by at least 1 equivalent of HCl toprovide the free acid compound, and reacting the mono free acid with anacid reducing agent such as BF3-THF to produce the correspondingaldehyde of the formula:

[0120] (e) reacting the aldehyde with a 2-halogenoctanoate (such asethyl 2-bromooctanoate) to produce a ketone compound of the formula:

[0121] (f) reducing the 3 ketone derivative with NaBH4, or the like,then removing the P¹ protecting group from the 5 hydroxy in a solventsuch as an alcohol, e. g. , ethanol in the presence of an acid catalystsuch as pyridinium-4-toluenesulphoneate or tetrabutylammonium fluoridetrihydrate in THF while heating at about 50-65° C. followed byhydrogenating the ester group with hydrogen and Pd/C to yield the freeacid diol as follows:

[0122] (g) and then cyclizing the 5R alcohol with the free acid toprovide a 6R pyranolone ring by heating the free acid compound at atemperature from 50° C. to 60° C. in ethanol in the presence oftoluene-4-sulfonic acid to provide a compound of the formula:

[0123] which may be utilized as the formula (II) compound describedabove.

[0124] Alternatively, the chiral ketone reducing agent utilized toreduce the beta oxo dodecanoic acid can be omitted to obtain a racemate.The racemate can be utilized as the formula (II) compound, followed byresolving the resulting (2S, 3S, 5R) formula (IV) enantiomer from its(2R, 3R, 5S) formula (VII) enantiomer.

[0125] Another process for making an intermediate compound forsynthesizing a compound of the formula:

[0126] comprises the steps of:

[0127] (a) treating dodecyl halide (lauric acid chloride) with aN,O-dimethylhydroxyl-amine hydrochloride in a 1:1.5 ratio inacetonitrile, triethylamine and1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and stirringat room temperature for about 5 hours to provide a compound of theformula:

[0128] (b) reacting the N-methoxymethyl amide carboxylic acid derivativewith an organometallic salt of an acetic acid R ester (or a salt of atwo halo acetic acid R ester), such as 2-lithium acetic acid ethyl esterin a suitable solvent such as dry THF under nitrogen or argon and thereaction is quenched with an acid such as HCl to produce a ketonederivative of the formula:

[0129] (c) forming the tetradecyl acyl halide (for example the acidchloride) of the ketone compound and reacting it with aN,O-dimethylhydroxyl-amine hydrochloride in a 1:1.5 ratio inacetonitrile, triethylamine and1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and stirringat room temperature for about 5 hours to provide a compound of theformula:

[0130] (d) reacting the N-methoxymethyl amide carboxylic acid derivativewith an alpha organometallic salt of an lower alkyl acid R ester (or asalt of an alpha halo lower alkyl acid R ester), such as 2-lithiumoctanoic acid ethyl ester in a suitable solvent such as dry THF undernitrogen or argon and quenching the reaction with an acid such as HCl,and the like to produce a 3,5 diketone derivative of the formula:

[0131] (e) reducing the 3,5 diketone acid derivative with NaBH₄, or thelike, to yield the free acid diol as follows:

[0132] and

[0133] (f) cyclizing the 5RS alcohol with the free acid to provide a 6Rpyranolone ring by heating the free acid compound at a temperature from50° C. to 60° C. in ethanol in the presence of toluene-4-sulfonic acidto provide a compound of the formula:

[0134] which may be utilized as the formula (II) compound describedabove.

[0135] Alternatively, the diketone reduction step of step (e) can beconducted with a chiral borane reducing to obtain a (2RS, 3R, 5R) whichwhen cyclized provides the (3RS, 4R, 6R) compound, which can be utilizedas the formula (II) compound.

[0136] A further process for making an intermediate compound forsynthesizing a compound of the formula:

[0137] comprises the steps of:

[0138] (a) reacting methyl 2-acetyloctanoate (Aldrich 10887) with aorganometallic base, such as butyllithium salt to deprotonate thetertiary carbon atom of the 2-acetyl group,

[0139] (b) reacting the lithium organometallic salt in a suitablesolvent such as THF with a lauric acid halide (dodecoyl chloride) of theformula:

[0140] to provide a 3,5 diketone compound of the formula:

[0141] (c) reducing the 3,5 diketone acid derivative with NaBH₄, or thelike, to yield the free acid diol as follows:

[0142] and

[0143] (d) cyclizing the 5RS alcohol with the free acid to provide a 6Rpyranolone ring by heating the free acid compound at a temperature from50° C. to 60° C. in ethanol in the presence of toluene-4-sulfonic acidto provide a compound of the formula:

[0144] which may be utilized as the formula (II) compound describedabove.

[0145] Alternatively, the diketone reduction step of step (c) can beconducted with a chiral borane reducing agent to obtain a (2RS, 3R, 5R)which when cyclized provides the (3RS, 4R, 6R) compound, which can beutilized as the formula (II) compound.

[0146] In one aspect of the present invention, there is provided achiral alcohol resolution process step which incorporates a lipase tohydrolyze esters of the intermediate alcohols, or to be present duringan esterification step, wherein the lipase may be a lipase such as thepseudomonas PS 30, pig pancreas lipase, and the like.

[0147] The (2S, 3S, 5S) oxetanone compounds provided by the processesaccording to the invention may be linked to other compounds or a supportby esterifying with an acyl, acyl halide, or by a transesterificationprocess. In a preferred embodiment the lipase inhibitiors according tothe invention are linked via a terminal ether/terminal ester bridge, toa oil or lipid absorbable polymer moiety. Preferably, the free5-hydroxyl (2S, 3S, 5S) compounds are linked under acidic conditions toa polysaccharide such as chitosan, which polysaccharide has beenmodified to have an acyl, or acyl halide attachment group.

[0148] Non-limiting examples of preferred bridges between the lipaseinhibitor oxetanone moiety produced according to the present inventionand the polymer moiety includes at least one ether bridge formed from analcohol group on the polymer moiety and at least one ester orcarboxamide bond between the 5-hydroxy group of the oxetanone. Furtherpreferred is a process for producing a compound wherein at least oneamino acid derivative is located in the bridge, and is bound directly orindirectly to the 5 hydroxyl position on the 1,3 oxetanone moiety via anester linkage.

[0149] The preferred compounds produced from such linkage with apolysaccharide also includes their pharmaceutically acceptable isomers,hydrates, solvates, salts and prodrug derivatives.

[0150] A preferred aspect of the present invention relates to a processfor making novel oxetanone derivatives of the formula Ia, as follows:

[0151] wherein:

[0152] t is an integer from 0 to 1

[0153] X-O-Q is an ether linkage wherein:

[0154] X of the ether linkage is a bridging group, and

[0155] Q of the ether linkage is a polysaccharide of a sufficientmolecular weight or property that such polysaccharide is not absorbed bythe digestive system of a mammal such as a dog, cat, non-human primateor a human primate, which polysaccharide is further defined below;

[0156] R¹ and R³ is defined as in formula (I) of the (2S, 3S, 5S)5-hydroxyl oxetanone compounds, produced by a process according to theinvention as described above,;

[0157] R^(1a) is a member selected from the group consisting of:

[0158] Hydrogen,

[0159] Ar,

[0160] Ar—C₁₋₅-alkyl and

[0161] C₁₋₁₀-alkyl interrupted by 0-3 members independently selectedfrom the group consisting of an oxygen atom, a sulfur atom, a sulfinylgroup, a sulfonyl group, a-N(—R^(4a))— group, a —C(═O)—N(—R^(4a))—group, and a —N(—R^(4a))—C(═O)— group, wherein 0-3 carbon atoms of theC₁₋₁₀-alkyl group can be substituted independently by a member selectedfrom the group consisting of a hydroxy group, thiol group, C₁₋₁₀-alkoxygroup, a C₁₋₁₀-alkylthio group, a —N(—R^(5a),—R^(6a)) group, a —C(═O)—N(—R^(7a), —R^(8a)) group and a —N(—R^(9a))—C(═O)—R^(10a) group;

[0162] R^(2a) is a member selected from the group consisting of:

[0163] hydrogen and C₁₋₆-alkyl, or R^(2a) taken with R^(1a) forms a 4-6membered saturated ring containing 0-4 nitrogen atoms wherein the ringmay be substituted by 0-4 R¹¹ groups;

[0164] R^(4a)-R^(10a) are each independently a member selected from thegroup consisting of:

[0165] hydrogen and C₁₋₆-alkyl;

[0166] n is an integer of 0-3;

[0167] and all pharmaceutically acceptable isomers, salts, hydrates,solvates and prodrug derivatives thereof.

[0168] A preferred compound according to formula Ia is a compoundwherein X is a member selected from the group consisting of:

—(C(═O))₀₋₁—X_(a)—,

[0169] wherein X_(a) is a member selected from the group consisting of:

[0170] a straight or branched chained divalent C₁₋₁₇-alkylene groupwhich is saturated or optionally interrupted by up to eight double ortriple bonds;

[0171] a straight or branched chained divalent C₁₋₁₇-alkylene groupwhich is saturated or optionally interrupted by one or more membersselected from the group consisting of:

[0172] an oxygen atom,

[0173] a sulfur atom,

[0174] a sulfonyl group,

[0175] a sulfinyl group,

[0176] a substituted or unsubstituted 6-10 member monocyclic or bicyclicaryl or heteroaryl group having from 1-4 ring hetero atoms selected fromthe group consisting of O, N, S,

[0177] a —NH— group, wherein the hydrogen atom may be replaced with aC₁₋₁₀ alkyl group

[0178] a —C(═O)— group,

[0179] a —NH—C(═O)— group, wherein the hydrogen atom may be replacedwith a C₁₋₁₀ alkyl group and

[0180] a —C(═O)—NH— group, wherein the hydrogen atom may be replacedwith a C₁₋₁₀ alkyl group

[0181] a straight or branched chained divalent C₁₋₁₇-alkylene groupwhich is saturated or optionally interrupted by up to eight double ortriple bonds and is interrupted in a position other than alpha to anunsaturated carbon atom by one or more members selected from the groupconsisting optionally interrupted by one or more members selected fromthe group consisting of:

[0182] an oxygen atom,

[0183] a sulfur atom,

[0184] a sulfonyl group,

[0185] a sulfinyl group,

[0186] a substituted or unsubstituted 6-10 member monocyclic or bicyclicaryl or heteroaryl group having from 1-4 ring hetero atoms selected fromthe group consisting of O, N, S,

[0187] a —NH— group, wherein the hydrogen atom may be replaced with aC₁₀ alkyl group

[0188] a —C(═O)— group,

[0189] a —NH—C(═O)— group, wherein the hydrogen atom may be replacedwith a C₁₋₁₀ alkyl group and

[0190] a —C(═O)—NH— group, wherein the hydrogen atom may be replacedwith a C₁₋₁₀ alkyl group

[0191] divalent phenylene or divalent naphthylene substituted on thering structure by 0-4 members selected from the group consisting of—C₁₋₆-alkyloxy-C₁₋₆-alkyl, —C₁₋₆-alkylthio-C₁₋₆-alkyl, —C₁₋₆-alkyl-OHand —C₁₋₆-alkyl-SH; divalent biphenylene substituted by 0-6 membersselected from the group consisting of —C₁₋₆-alkyloxy-C₁₋₆-alkyl,—C₁₋₆-alkylthio-C₁₋₆-alkyl, —C₁₋₆-alkyl-OH and —C₁₋₆-alkyl-SH;

[0192] phenoxyphenylene substituted by 0-6 members selected from thegroup consisting of —C₁₋₆-alkyloxy-C₁₋₆-alkyl,—C₁₋₆-alkylthio-C₁₋₆-alkyl, —C₁₋₆-alkyl-OH and —C₁₋₆-alkyl-SH;

[0193] divalent phenylthiophenylene substituted by 0-6 members selectedfrom the group consisting of —C₁₋₆-alkyloxy-C₁₋₆-alkyl,—C₁₋₆-alkylthio-C₁₋₆-alkyl, —C₁₋₆-alkyl-OH and —C₁₋₆-alkyl-SH; and

[0194] and all pharmaceutically acceptable isomers, salts, hydrates,solvates and prodrug derivatives thereof.

[0195] More preferred is compound according to formula Ia wherein X is amember selected from the group consisting of:

—(C(═O))—X_(a)—,

[0196] and X_(a) is a member selected from the group consisting of:

[0197] a straight or branched chained divalent C₁₋₁₇-alkylene groupwhich is saturated or optionally interrupted by up to eight double ortriple bonds.

[0198] Further preferred are compounds according to formula Ia, whereinR¹ is undecyl, R³ is hexyl,R^(1a) is straight or branched chain C₁-C₈alkyl, R^(2a) is hydrogen and X is a member selected from the groupconsisting of:

—(C(═O))—X_(a)—,

[0199] and Xa is a member selected from the group consisting of divalentsaturated C₅-C₁₈ alkylene, and more preferably, Xa is a divalentsaturated pentylene or undecylene group, or a salt thereof.

[0200] Preparation of Compounds

[0201] The lipase inhibitor compounds, polymer moieties and bridginggroups of the present invention may be synthesized or readily obtainedfrom commercially available sources. Preferably, the (2S, 3S, 5S)5-hydroxyl oxetanone lipase inhibitor compounds are obtained by aprocess as described above. Polymer bridging groups, bridge couplingprocesses and compound purification methods are described and referencedin standard textbooks, particularly the coupling of alcohol groups viadiether bridges, ether/ester bridges, ether/ketone bridges and the like.Standard polymer textbooks reference typical bifunctional bridginggroups and coupling procedures.

[0202] Starting materials used in any of these methods are commerciallyavailable from chemical vendors such as Aldrich, Sigma, NovaBiochemicals, Bachem Biosciences, and the like, or may be readilysynthesized by known procedures.

[0203] Reactions are carried out in standard laboratory glassware andreaction vessels under reaction conditions of standard temperature andpressure, except where otherwise indicated.

[0204] During the synthesis of these compounds, the functional groupsmay be protected by blocking groups to prevent cross reaction during thecoupling procedure. Examples of suitable blocking groups and their useare described in “The Peptides: Analysis, Synthesis, Biology”, AcademicPress, Vol. 3 (Gross, et al., Eds., 1981) and Vol. 9 (1987), thedisclosures of which are incorporated herein by reference. Alcohol andester protecting group may also be utilized.

[0205] Lipase inhibitor moieties having a free hydroxy group such as theoxetanones described above, and the like, are easily coupled to apolymer moiety having free hydroxy groups such as cellulose, chitosanand other polysaccharides having free hydroxyl groups. One or both ofthe lipase inhibitor moiety and the polymer moiety may be derivitized toform part of the linking bridge prior to reacting with the other moiety.For example, a desired number of the hydroxy groups of thepolysaccharides, such as chitosan, may be functionalized with a compoundhaving a terminal acyl or ester group such as 6-bromohexanoic acid,12-bromododecanoic acid, and the like, or an ester derivative of suchacids, and subsequently the 5-hydroxyl group of the oxetanone lipaseinhibitor molecule may be condensed with the ester group or a terminalacyl group (the acyl group may be modified with an halide group to anacyl halide group, such as the acyl chloride) to form an ester linkagewith the ether bridged polymer moiety as shown in polysaccharidechemistry. In one procedure a polymer moiety such as chitosan can bereacted with a compound such as a halomethylbenzoic acid ester,loweralkyl 6-bromohexanoic acid, lower alkyl 12-bromododecanoic acid, orthe like, and de-esterified to present a free acid group which may be,activated further by forming the acyl halider, and reacted with aterminal portion of the lipase inhibitor (which may have been esterifiedwith a bridging compound which has a functional group capable ofreacting with an ester or acyl group) to form an ester, ketone, orcarboxamide with the optionally derivitized lipase inhibitor moiety.

[0206] In one preferred aspect of the invention, one of the two moietiesis reacted with an asymmetrical halide/acyl bridging group, such as aterminal halide alkanoic acid of 1:1 to etherize a free hydroxyl group,replace a hydrogen atom on an amino group, or foom a ketone with an acidgroup, and the resulting intermediate can then be reacted with the analcohol or amino moiety to form an ester group or a carboxamide groupwith a free alcohol group, or by replacing a nitrogen atom on a aminogroup. Particularly preferred polymer moieties are polysaccharideshaving multiple free hydroxyl group which after coupling may optionallybe sulfonated to render the lipase moiety itself a lipase inhibitorcompound. Etherification, amination and ketone formation procedures arewell-known in the art and well within the routine skill of the ordinarypractitioner. Further, other bridging groups and the techniques forbinding a compound having a reactive functional group to a polymermoiety are well-known in the art. The preferred compounds also includetheir pharmaceutically acceptable isomers, hydrates, solvates, salts andprodrug derivatives.

[0207] The bridging group refers to a bifunctional chain or spacer groupcapable of reacting with one or more functional groups on a lipaseinhibitor compound and then react with a second same or differentfunctional group on a polymer compound in order to form a linkedstructure or conjugate between the two compounds. The bond formedbetween the bridging group and each of the two compounds is preferablyof a type that is resistant to cleavage by the digestive environment,other than to inhibit a lipase by binding substantially irreversibly.

[0208] By appropriate selection of the type of bridging group reactant,different structural groups with various chemical properties can beincorporated into the resulting bridge and various types of lipaseinhibitors can be connected to a nonabsorbable polymer moiety, such as apolysaccharide, and preferably to chitosan. Reaction temperatures andother reactions conditions, as well are reactant proportions are wellwithin the skill of the ordinary polymer chemist practitioner. Othergroups and modifications will be apparent to one of ordinary skill inthe art from the above discussion.

[0209] The lipase inhibitor functionality of the coupled lipaseinhibitors may be determined by well-known lipase inhibitor assays. Atherapeutically effective amount of the bound lipase inhibitor may beadministered to a patient. Additional fat binding polymers mayoptionally be added to the composition.

[0210] The following non-limiting reaction Schemes I, II, III and IVillustrate preferred embodiments of the invention with respect to makingcompounds according to the invention.

[0211] Such chitosan derivatives provide a lipase inhibitor with verylow absorption rates, and at such rates tetrahydroesterastin is notknown to be substantially toxic.

[0212] Dosage formulations of the compounds of this invention to be usedfor therapeutic administration must be sterile. Sterility is readilyaccomplished by filtration through sterile membranes such as 0.2 micronmembranes, or by other conventional methods. Formulations typically willbe stored in lyophilized form or as an aqueous solution. The pH of thepreparations of this invention typically will be between 3 and 11, morepreferably from 5 to 9 and most preferably from 7 to 8. It will beunderstood that use of certain of the foregoing excipients, carriers, orstabilizers will result in the formation of cyclic polypeptide salts.While the preferred route of administration is by oral tablets, capsulesor other unit dose mechanisms, such as liquids, other methods ofadministration are also anticipated such as in food stuffs, employing avariety of dosage forms. The compounds of this invention are desirablyincorporated into food articles which may include fats to prevent theirabsorption.

[0213] The compounds of this invention may also be coupled with suitablepolymers to enhance their therapeutic effects. Such polymers can includelipophilic polymers, such as polysaccharides and the like.

[0214] Therapeutically effective dosages may be determined by either invitro or in vivo methods. For each particular compound of the presentinvention, individual determinations may be made to determine theoptimal dosage required. The range of therapeutically effective dosageswill naturally be influenced by the route of administration, thetherapeutic objectives, and the condition of the patient. For routes ofadministration, the lipase inhibitor activity, in view of the amount offat consumed, must be individually determined for each inhibitor bymethods well known in pharmacology. Accordingly, it may be necessary forthe therapist to titer the dosage and modify the route of administrationas required to obtain the optimal therapeutic effect. The determinationof effective dosage levels, that is, the dosage levels necessary toachieve the desired result, will be within the ambit of one skilled inthe art. Typically, applications of compound are commenced at lowerdosage levels, with dosage levels being increased until the desiredeffect is achieved.

[0215] Typically, about 500 mg to 3 g of a lipase inhibitor compound ormixture of lipase inhibitor compounds of this invention, as the freeacid or base form or as a pharmaceutically acceptable salt, iscompounded with a physiologically acceptable vehicle, carrier,excipient, binder, preservative, stabilizer, dye, flavor etc., as calledfor by accepted pharmaceutical practice. The amount of active ingredientin these compositions is such that a suitable dosage in the rangeindicated is obtained. The addition, one or more other therapeuticingredients such as a fat absorbing polysaccharide or fiber, afat-specific lipase inhibitor or lipase, as well as other dietary agentsmay be utilized in therapeutically effective amounts.

[0216] Typical adjuvants which may be incorporated into tablets,capsules and the like are a binder such as acacia, corn starch orgelatin, and excipient such as microcrystalline cellulose, adisintegrating agent like corn starch or alginic acid, a lubricant suchas magnesium stearate, a sweetening agent such as sucrose or lactose, ora flavoring agent. When a dosage form is a capsule, in addition to theabove materials it may also contain a liquid carrier such as water,saline, a fatty oil. Other materials of various types may be used ascoatings or as modifiers of the physical form of the dosage unit.Sterile compositions for injection can be formulated according toconventional pharmaceutical practice. Buffers, preservatives,antioxidants and the like can be incorporated according to acceptedpharmaceutical practice.

[0217] In practicing the methods of this invention, the compounds ofthis invention may be used alone or in combination, or in combinationwith other therapeutic or diagnostic agents. In certain preferredembodiments, the compounds of this inventions may be coadministeredalong with other compounds typically prescribed for these conditionsaccording to generally accepted medical practice, such as other weightcontrol or lipase inhibitory products, cholesterol controlling drugs,and the like.

[0218] The compounds of this invention can be utilized in vivo,ordinarily in mammals such as non-human primates, humans, sheep, horses,cattle, pigs, dogs, cats, rats and mice, or in vitro.

[0219] The following non-limiting examples are provided to betterillustrate the present invention.

EXAMPLE 1 Production of mixed hexyl 3-oxo-tetradecanoate esters

[0220] To a 20 L 3-neck flask equipped with a mechanical stirrer, argoninlet, reflux condenser, heating mantle and vacuum system, under argonis added a suspension 140 g of sodium hydride in 6 L of THF. Thetemperature is lowered to 0-5° C. and maintained as 1 Kg of mixed hexylacetic acid esters (Aldrich 461253) are slowly added to this suspensionwith stirring. After one hour of stirring the mixture is cooled −10° C.and 1.25 Kg of 24% w/wn-Butyllithium (n-BuLi) (about 5 mol) in 3 L ofhexane is added. After stirring at this temperature for 45 minutes, theflask is then cooled to below −15° C. followed by slowly adding 575 g ofethyl dodecanoate (Aldrich L4625). This solution is allowed to warm to−10° C. with stirring and is stirred at this temperature for 1 hour. Thereaction solution is added under argon 1.25 L of 40% hydrochloric acidand 1.5 Kg of ice. The mixture is extracted twice with 5 L of hexane andwater. The organic phases are combined, dried over magnesium sulfate,filtered, and the organic solvents are evaporated at reduced pressure toprovide a solid residue (about 1.4 Kg).

EXAMPLE 2 Production of (3R) 3-hydroxy-tetradecanoic acid

[0221] To a 20 L 3-neck flask equipped with a mechanical stirrer, argoninlet, reflux condenser, heating mantle, cooling apparatus, and vacuumsystem, under argon is added 8 mols (2.6 Kg) of(+)-β-chlorodiisopinocamphenylborane (“+-DIP—Cl”). To this was added 4 Lof dry THF at room temperature over one hour. Once the mixture isdissolved together the temperature is lowered to −25° C. Whilemaintaining the temperature between −20 and −25° C. the 1.4 Kg of mixedhexyl 3-oxo-tetradecanoate esters (Example 1) in 2 L of dry THF isslowly added with stirring (over a one hour period) to this solution.The reaction temperature is maintained between −10 and −20° C. for 8hours and the reaction progress is monitored with HPLC. After the 8hours, the temperature is allowed to gradually warm to about −5° C. andafter 1 hour at this new temperature is allowed to warm to 0° C. inorder to increase the rate of reaction. The reaction process ismonitored by HPLC and the reaction is stopped after all the startingmaterial is consumed. To the reaction mixture is slowly added 3 L ofwater (over a one hour period) while maintaining the reactiontemperature below 10° C. About 4 L of methanol is then added, followedby 4 L of aqueous 5 M NaOH. The mixture is stirred at room temperatureand the reaction is monitored by HPLC until it is complete (about twohours). The reaction mixture is allowed to separate and the aqueouslayer is removed. The aqueous layer is extracted with hexane and theseparated aqueous layer is neutralized with HCl, saturated with NaCl andextracted 3 times with 3×1 L of with warm hexane. The hexane layers arecombined and concentrated by evaporation of the solvent at reducedpressure to provide a crude product which is dried over magnesiumsulfate to provide about 1.3 Kg of solid.

EXAMPLE 3 Production of (3R)-3-benzoyloxy-tetradecanoyl chloride

[0222] To a 20 L 3-neck round bottom flask equipped with a mechanicalstirrer, nitrogen inlet, reflux condenser, heating mantle, vacuumsystem, and scrubber system for efficient removal of HCl and SO₂ gasesliberated during the reaction, is charged under nitrogen 15 moles ofbenzoic acid anhydride, 10 moles of concentrated anhydrous HCl in 4 L ofTHF, and 7.48 moles of the (3R)-3-hydroxy-tetradecanoic acid obtainedfrom Example 1, above. The stirred mixture is placed under a N₂ flow,which is vented to the scrubber system. The stirred mixture is heated toreflux for 3 hours during which the reaction becomes complete. Theresulting solution is neutralized with 1N NaOH and the organic layer isseparated from the aqueous layer. The aqueous layer is washed with THFand the resulting organic portions are combined, placed under vacuum andTHF is removed. The resulting solid is dissolved in warm hexane, cooledand worked up to provide the product (3R)-3-benzoyloxy-tetradecanoylchloride in about 95% yield.

EXAMPLE 4 Production of 5R ethyl5-benzoyloxy-2-hexyl-3-oxo-hexadecanoate ester

[0223] To a 20 L 3-neck flask equipped with a mechanical stirrer, argoninlet, reflux condenser, heating mantle and vacuum system, under argonis added a suspension 140 g of sodium hydride in 6 L of THF. Thetemperature is lowered to 0-5° C. and maintained as 1 Kg of ethyloctanoate (Aldrich 112321) is slowly added to this suspension withstirring. After one hour of stirring the mixture is cooled −10° C. and1.25 Kg of 24% w/wn-Butyllithium (n-BuLi) (about 5 mol) in 3 L of hexaneis added. After stirring at this temperature for 45 minutes, the flaskis then cooled to below −15° C. followed by slowly adding 575 g of the(3R) 3-benzoyloxy-tetradecanoyl chloride from Example 3. This solutionis allowed to warm to −10° C. with stirring and is stirred at thistemperature for 1 hour. The reaction solution is added under argon 1.25L of 40% hydrochloric acid and 1.5 Kg of ice. The mixture is extractedtwice with 5 L of hexane and water. The organic phases are combined,dried over magnesium sulfate, filtered, and the organic solvents areevaporated at reduced pressure to provide a solid residue (about 1 Kg).

EXAMPLE 5 Production of 5R 3,5-dihydroxy-2-hexyl-hexadecanoic acid

[0224] To a 20 L 3-neck flask equipped with a mechanical stirrer, argoninlet, reflux condenser, heating mantle and vacuum system, under argon 6L of anhydrous THF is added and 1 Kg of 5R ethyl5-benzoyloxy-2-hexyl-3-oxo-hexadecanoate ester is dissolved whilegassing with argon, treated with 250 mL of MeOH and cooled to −5° C.Then 825 g of sodium borohydride is slowly added in portions withstirring in a manner that permits the temperature to not exceed 0° C.After stirring for 3 hours the excess sodium borohydride is filteredoff, the reaction mixture is hydrolyzed (to about pH 6) with cold 2Nhydrochloric acid at 0° C. The mixture is allowed to warm to roomtemperature and the solvent was evaporated off under vacuum. The residueis extracted twice with ether and the ether phases are combined andconcentrated under vaccum. The crude concentrate is added to a solutionof THF and aqeuous KOH and stirred at 35° C. for three hours. Theorganic phase is separated, washed twice with cold water, dried overMgSO₄ and evaporated under reduced pressure. There is obtained about 1Kg of 5R 3,5-dihydroxy-2-hexyl-hexadecanoic acid.

EXAMPLE 6 Production of (6R)5,6-dihydro-3-hexyl-4-hydroxy-6-undecyl-2H-pyran-2-one

[0225] To a 20 L 3-neck flask equipped with a mechanical stirrer, argoninlet, reflux condenser, heating mantle and vacuum system, is chargedunder argon with 6 L of anhydrous toluene and the 1.3 Kg of product fromExample 5 is slowly added to the solution with stirring pyridiumpara-toluenesulfonate and refluxed under argon for 2 hours to form thelactone. The reaction mixture is cooled to room temperature and washedtwice with a saturated aqueous sodium carbonate solution. The organicphases are combined and evaporated under vacuum at about 40° C. toproduce a product, and warm hexane is added to the product to dissolveit into a homogenous mixture. The warm hexane mixture is cooled to roomtemperature with stirring. The mixture is then cooled to −10° C. andstirred at that temperature for 15 hours. The crystalline solid is thenfiltered under suction. The filter cake is washed with cold hexane anddried over magnesium sulfate. The crystals are then dried overnight in adrier to remove any remaining solvent. About 1 Kg of (6R)5,6-dihydro-3-hexyl-4-hydroxy-6-undecyl-2H-pyran-2-one, having a m.p. of106-108° C. is provided.

EXAMPLE 7 Production of (3S, 4S, 6R)tetrahydro-3-hexyl-4-hydroxy-6-undecyl-2H-pyran-2-one

[0226] A hydrogenator is purged twice with nitrogen and charged with the1 Kg of product from Example 6, which is dissolved in 6 L of anhydrousethyl acetate, and 500 g of PtO₂ is added. The hydrogenator is purgedtwice with hydrogen and then charged with hydrogen at 50 bar. Thetemperature is raised to 40° C. and hydrogen flow is maintained at 50bar for 12 hours. The catalyst is filtered off and the solution isevaporated. After dissolving in warm hexane, the product is cooled to 0°C. overnight and recrystallized to yield 900 g of (3S, 4S, 6R)tetrahydro-3-hexyl-4-hydroxy-6-undecyl-2H-pyran-2-one, having a m.p. of108-109° C.

EXAMPLE 8 Production of (3S, 4S, 6R)tetrahydro-3-hexyl-4-[(tetrahydro-2H-pyran-2-yl)oxy]-6-undecyl-2H-pyran-2-one

[0227] The 900 g of (3S, 4S, 6R)tetrahydro-3-hexyl-4-hydroxy-6-undecyl-2H-pyran-2-one of Example 7, and500 ml of freshly distilled 3,4-dihydro-2H-pyran are dissolved in 10 Lof methylene chloride and cooled to about 3° C. and 9.6 g ofp-toluenesulfonic acid monohydrate are added. The temperature rises toabout 8° C. and the mixture is stirred at this temperature until thereaction is finished. The reaction mixture is washed with a mixture of 4L of saturated aqueous sodium chloride solution, 4 L of saturatedaqueous sodium hydrogen carbonate solution and 8 L of water. Afterdrying the mixture over MgSO₄ the mixture is filtered and the solvent isremoved. The resulting residue is utilized in the next step withoutfurther purification of the (3S, 4S, 6R)tetrahydro-3-hexyl-4-[tetrahydro-2H-pyran-2-yl) oxy]-6-undecyl-2H-2-one.

EXAMPLE 9 Production of benzyl (2S, 3S, 5R)2-hexyl-5-hydroxy-3-[(tetrahydro-2H-pyran-2-yl)oxy]-hexadecanoic acidester

[0228] The product of Example 8 is dissolved in 6 L of THF under argonand anhydrous conc. sulphuric acid is added which is warmed to 30° C.and stirred for two hours. A metallic salt of benzyl alcohol (sodiumsalt) in an aqueous solution is slowly added in a 1:1.2 molar excesswith respect to the hexadecanoic acid ester. The mixture is stirred for4 hours at 25° C. the pH is then adjusted to 9 with NaOH, and theaqueous layer and organic layer are separated. The organic layer isextracted twice with 4 L of cold H₂O, and the organic layer is driedover magnesium sulfate. The resulting benzyl (2S, 3S, 5R)2-hexyl-5-hydroxy-3-[(tetrahydro-2H-pryan-2-yl)oxy] hexadecanoic acidester is used in the next step without purification.

EXAMPLE 10 Production of benzyl (2S, 3S, 5S)5-benzoyloxy-2-hexyl-3-[(tetrahydro-2H-pyran-2-yl)oxy]-hexadecanoic acidester

[0229] The product of Example 9, triphenylphosphine (1.5 Kg) and benzoicacid (600 g) are dissolved in 6 L of THF, and to the resultant solution,is added a solution of 800 g of diethyl azodicarbonate in 1 L of THF.The mixture is stirred at room temperature for 15 hours, and reactionmixture is concentrated under reduced pressure. The concentrate isdissolved in warm hexane/THF and the mixture is extracted with water anda saturated NaCl solution. The organic phase is dried over magnesiumsulfate and the solvent is distilled off under vacuum to provide aconcentrate containing benzyl (2S, 3S, 5S)5-benzoyloxy-2-hexyl-3-[(tetrahydro-2H-pyran-2-yl)oxy]-hexadecanoic acidester which is used in the next step without purification.

EXAMPLE 11 Production of (2S, 3S, 5S)5-benzoyloxy-2-hexyl-3-[(tetrahydro-2H-pyran-2-yl) oxy]-hexadecanoicacid

[0230] The benzyl ester of Example 10 is dissolved in anhydrous 5 L ofTHF and HCl is added in an equimolar amount with respect to the benzylester. Under argon the ester is hydrogenated at room temperature forthree hours by stirring the solution in the presence of Pd/C 10%. Thesolution is filtered and the catalyst is washed with THF, the washingsare combined with the reaction mixture and the reaction mixture isneutralized with aqueous IN NaOH. The organic layer is separated, driedover MgSO₄ and the solvent is evaporated under vacuum to provide a crudecomposition of(2S, 3S, 5S)5-benzoyloxy-2-hexyl-3-[(tetrahydro-2B-pyran-2-yl)oxy]-hexadecanoicacid, which is used in the next step without further purification.

EXAMPLE 12 Production of (2S, 3S, 5S)5-benzoyloxy-2-hexyl-4-hydroxyhexadecanoic 1,3 -lactone, i.e., (3S,4S)3-hexyl-4-[(S) 2-benzoyloxytridecyl]-2-oxetanone

[0231] 500 g of the hexadecanoic acid of Example 11 is dissolved in 6 Lof anhydrous ethanol and 30 g of toluene-4-sulfonic acid anhydride isadded. The temperature of the reaction mixture is raised to 60° C. withstirring and maintained at 55-65° C. until the reaction is finished. Thesolvent is removed under vacuum and the residue is dissolved in warmhexane. The mixture is stirred for 2 hours cooled to -10° C. and allowedto stand overnight at 0° C. The crystals are removed from the solvent byfiltration and washed with cold hexane to yield the compound (2S, 3S,5S) 5-benzoyloxy-2-hexyl-4-hydroxyhexadecanoic 1,3-lactone.

EXAMPLE 13 Production of (2S, 3S, 5S) 3,5-dihydroxy-2-hexylhexadecanoic1,3-lactone, i.e., (3S, 4S) 3hexyl-4-[(S) 2-hydroxytridecyl]-2-oxetanone

[0232] 200 g of the (2S, 3S, 5S)5-benzoyloxy-2-hexyl-4-hydroxyhexadecanoic 1,3-lactone of Example 12 issuspended in a 4 L solution containing 0.01 N sodium hydroxide dissolvedin a mixture of water-dioxane (1:1), and the resulting mixture isstirred at about 25° C. for about 12 hours to effect the hydrolysis ofthe benzoyloxy group to an alcohol group. The rection mixture isextracted 3 times with 2 L portions of hexane and the extracts arecombined. After concentration of the extracts to dryness the solid isdissolved in warm hexane, cooled to 0° C. and stirred for 2 hours. Themixture is seeded with pure (2S, 3S, 5S)3,5-dihydroxy-2-hexylhexadecanoic 1,3-lactone crystals and the mixtureis allowed to sit overnight at 0° C. The crystals are filtered, washedwith cold hexane and dried to produce about 125 g of (2S, 3S, 5S)3,5-dihydroxy-2-hexylhexadecanoic 1,3-lactone, i.e., (3S, 4S)3-hexyl-4-[(S) 2 -hydroxytridecyl]-2-oxetanone.

EXAMPLE 14 Production of ethyl 3,5-di-oxo-2-hexyl-hexadecanoate ester

[0233] To a 20 L 3-neck flask equipped with a mechanical stirrer, argoninlet, reflux condenser, heating mantle and vacuum system, under argonis added a suspension 140 g of sodium hydride in 6 L of THF. Thetemperature is lowered to 0-5° C. and maintained as 1 Kg of methyl2-acetyloctanoate (Aldrich 10887) is slowly added to this suspensionwith stirring. After one hour of stirring the mixture is cooled −10° C.and 1.25 Kg of 24% w/wn-Butyllithium (n-BuLi) (about 5 mol) in 3 L ofhexane is added. After stirring at this temperature for 45 minutes, theflask is then cooled to below −15° C. followed by slowly adding 575 g ofethyl dodecanoate (Aldrich L4625). This solution is allowed to warm to−10° C. with stirring and is stirred at this temperature for 1 hour. Thereaction solution is added under argon 1.25 L of 40% hydrochloric acidand 1.5 Kg of ice. The mixture is extracted twice with 5 L of hexane andwater. The organic phases are combined, dried over magnesium sulfate,filtered, and the organic solvents are evaporated at reduced pressure toprovide a solid residue (about 1.4 Kg).

EXAMPLE 15 Production of (3R, 5R) ethyl3,5-di-hydroxy-2-hexyl-hexadecanoate ester

[0234] To a 20 L 3-neck flask equipped with a mechanical stirrer, argoninlet, reflux condenser, heating mantle, cooling apparatus, and vacuumsystem, under argon is added 8 mols (2.6 Kg) of(+)-β-chlorodiisopinocamphenylborane (“+-DIP—Cl”). To this was added 4 Lof dry THF at room temperature over one hour. Once the mixture isdissolved together the temperature is lowered to −25° C. Whilemaintaining the temperature between −20 and −25° C. the 1.4 Kg of ethyl3,5-dioxo-tetradecanoate ester (Example 14) in 2 L of dry THF is slowlyadded with stirring (over a one hour period) to this solution. Thereaction temperature is maintained between −10 and −20° C. for 8 hoursand the reaction progress is monitored with HPLC. After the 8 hours, thetemperature is allowed to gradually warm to about −5° C. and after 1hour at this new temperature is allowed to warm to 0° C. in order toincrease the rate of reaction. The reaction process is monitored by HPLCand the reaction is stopped after all the starting material is consumed.To the reaction mixture is slowly added 3 L of water (over a one hourperiod) while maintaining the reaction temperature below 10° C. About 4L of methanol is then added, followed by 4 L of aqueous 5 M NaOH. Themixture is stirred at room temperature and the reaction is monitored byHPLC until it is complete (about two hours). The reaction mixture isallowed to separate and the aqueous layer is removed. The aqueous layeris extracted with hexane and the separated aqueous layer is neutralizedwith HCl, saturated with NaCl and extracted 3 times with 3×1 L of withwarm hexane. The hexane layers are combined and concentrated byevaporation of the solvent at reduced pressure to provide a crudeproduct which is dried over magnesium sulfate to provide about 1.3 Kg ofsolid.

EXAMPLE 16 Production of (4R, 6R)tetrahydro-3-hexyl-4-hydroxy-6-undecyl-2H-pyran-2-one

[0235] To a 20 L 3-neck flask equipped with a mechanical stirrer, argoninlet, reflux condenser, heating mantle and vacuum system, is chargedunder argon with 6 L of anhydrous toluene and the 1.3 Kg of product fromExample 15 is slowly added to the solution with stirring pyridiumpara-toluenesulfonate and refluxed under argon for 2 hours to form thelactone. The reaction mixture is cooled to room temperature and washedtwice with a saturated aqueous sodium carbonate solution. The organicphases are combined and evaporated under vacuum at about 40° C. toproduce a product, and warm hexane is added to the product to dissolveit into a homogenous mixture. The warm hexane mixture is cooled to roomtemperature with stirring. The mixture is then cooled to −10° C. andstirred at that temperature for 15 hours. The crystalline solid is thenfiltered under suction. The filter cake is washed with cold hexane anddried over magnesium sulfate. The crystals are then dried overnight in adrier to remove any remaining solvent. About 1 Kg of (4R, 6R)tetrahydro-3-hexyl-4-hydroxy-6-undecyl-2H-pyran-2-one, having a m.p. of95-96° C. is provided.

EXAMPLE 17 Production of (3S, 4S, 6R)tetrahydro-4-benzoyloxy-3-hexyl-6-undecyl-2H-pyran-2-one

[0236] A hydrogenator is purged twice with nitrogen and charged with the1 Kg of product from Example 9 dissolved in 6 L of anhydrous ethylacetate and 500 g of PtO₂ is added. The hydrogenator is purged twicewith hydrogen and then charged with hydrogen at 50 bar. The temperatureis raised to 40° C. and hydrogen flow is maintained at 50 bar for 12hours. The catalyst is filtered off and the solution is evaporated.After dissolving in warm hexane, the product is cooled to 0° C.overnight and recrystallized to yield 900 g of (3S, 4S, 6R)tetrahydro-3-hexyl-4-hydroxy-6-undecyl-2H-pyran-2-one, having a m.p. of108-109° C.

EXAMPLE 18 Production of (6S, 6R) 5,6dihydro-3-hexyl-6-undecyl-2H-pyran-2,4-dione

[0237] To a 20 L 3-neck flask equipped with a mechanical stirrer, argoninlet, reflux condenser, heating mantle and vacuum system, is chargedunder argon with 6 L of anhydrous acetone and 1 Kg of a (6S, 6R) racemicproduct prepared in a similar manner to the compound of Example 6, butfrom a (5R, 5S) racemic mixture of the compound described in Example 5.The temperature is lowered to about 20° C. and 1 L of Jones' reagent(chromic acid/conc. H₂SO₄ in acetone) is slowly added to the solutionwith stirring at an addition speed to maintain the temperature at lessthan 25° C. After addition of all of the Jones' reagent the mixture isstirred for 3 hours at 25° C. After completion of the reaction, thereaction mixture is poured into 15 L of H₂O. The lactone precipitatesout and is filtered off. After dissolving filter cake in a warmether/n-hexane solvent, the mixture is cooled and recrystallized toobtain 750 g of (6R) 5,6-dihydro-3-hexyl-6-undecyl-2H-pyran-2,4-dione,having a m.p. of 112.5-113.5° C.

EXAMPLE 19 Enzymatic resolution of (6S, 6R) 5,6dihydro-3-hexyl-6-undecyl-2H-pyran-2,4-dione

[0238] The compound of Example 18 is hydrogenated with Raney Nickil insubstantially the same manner as the procedure of Example 7, and the 4hydroxy group of the resulting compound is protected with atetrahydro-2H-pyran-2-yl ether group substantially as described inExample 8. The lactone ring is opened substantially as described inExample 9, and the 5R, 5S hydroxy group chirality is reversed with anester group which is sufficiently polar to render the compounds solublein a basic aqueous solvent by using shown the general procedures shownin Example 10. The benzyl alcohol group is removed from the acid groupby hydrogenation as described in Example 11 and the resulting free acid5S and 5R enantiomers are resolved in a basic aqueous medium by using alipase such as PS 30, pig liver lipase and the like.

[0239] After 45 to 48% of the total 5 hydroxy esters have been cleaved(about 90% of the 5S compounds) by the lipase, the insoluble 5S hydroxycompounds are separated from the reaction mixture and washed with water.Also, the remaining reaction mixture is filtered to remove the lipase,and the lipase mass is washed with water which is added to the aqueousfiltrte. The aqueous filtrate is set aside for further resolution.

[0240] The separated 5S hydroxy compounds, the aqueous insoluble portionare esterified with an excess of benzoic acid using the esterificationprocedures in an acidic H₂SO₄ and THF solvent. After completion of theesterification, the organic solution is washed with water, and separatedfrom the aqueous layer. The procedures of Examples 11 and 12 arefollowed to yield the (2S, 3S, 5S) 3,5-dihydroxy-2-hexylhexadecanoic1,3-lactone.

EXAMPLE 20 Recycling filtrate esters (greater than 90% 2R, 3R, 5Renantiomer) from the lipase separation

[0241] The aqueous filtrate from Example 20 is obtained and stirred in1N NaOH at 30° C. for 3 hours, neutralized with HCl and extracted withhexane. The hexane portions are combined and the solvent is evaporated.The procedures of Example 11 are followed to provide the compound (3R,4R, 6R) 5,6-dihydro 3-hexyl-4-[(tetrahydro-2H-pyran-2-yl)oxy]-undecanyl-2H-pyran-2-one, which can be recycled through the processesof Examples 7-13 to produce a composition having greater than 90-95% ofthe yield the (2S, 3S, 5S) 3,5-dihydroxy-2-hexylhexadecanoic1,3-lactone. Combining this 1,3 lactone product with the product ofExample 19 provide a composition having greater than 95 to 97% of the(2S, 3S, 5S) 3,5-dihydroxy-2-hexylhexadecanoic 1,3-lactone.

EXAMPLE 21

[0242] 10 grams of low viscosity chitosan (less than 500 cPs, readilyavailable commercially, e.g., ChitoClear™ by Primex) which is greaterthan 95% deacylated chitin is dissolved in a 500 milliliter flaskequipped with a stirrer thermometer and electrical heater, in a mixtureof 190 g of dimethylsulfoxide and 10 g of paraformaldehyde, at 50° C. Atthis temperature, after the addition of 0.1 g of finely powdered sodiumhydroxide, a solution of 1 g of 12-bromo-dodecanoic acid ethyl ester in10 g of dimethylsolfoxide is added over a period of about 30 minutes.The mixture is stirred for four hours at 50° C. The reaction mixture iscooled to room temperature, then poured into ethanol while the latter isbeing stirred vigorously. The solid is suction filtered, suspendedrepeatedly in ethanol until all the soluble substances are removed toyield a crude product. The crude product is stirred in an aqueous basic1 N sodium hydroxide ethanol solution, which is then acidified with HCluntil neutral pH for chitosan. The solid is washed twice with coldethanol and cold water, and the solid is then dried to yield about 10grams of ether functionalized chitosan. Analysis indicates that from 1%to 3% of the free hydroxyl groups on the chitosan polymeric backbone areetherified by the entry of the 12-dodecanoic acid group.

EXAMPLE 22

[0243] A colorless power of (2S, 3S, 5S)3,5-dihydroxy-2-hexyl-hexadecanoic 1,3-lactone (6 g), produced as inExample 13 above (or as described on pages 11 and 12 of U.S. Pat. No.4,202,824) is dissolved in 500 mL of THF to which is added Boc-(L)2-amino-4-methylpentanoic acid chloride (3 g, Boc-(L)-Leucine). Thereaction mixture is stirred and heated to reflux until HPLC indicatesthat the esterification is essentially complete. The organic phase isevaporated and the residue purified by chromatography on silica gel withtoluene-ethyl acetate to yield 5-[Boc-(L)2-amido-4-methylvaleryloxy]-2-hexyl-hexadecanoic 1,3-lactone (6 g).

EXAMPLE 23

[0244] The BOC group of the product (6 mg) of Example 2 is removed byhydrogenation at room temperature in 120 mL of THF in the presence of10% Pd/C. After hydrogenation is completed, the catalyst is filtered offand the filtrate is evaporated to yield a crude free amino groupproduct, which is taken up in 100 mL of THF. The functionalized chitosanproduct produced in Example 1 which has been converted to the acylchloride derivative is taken up in 200 mL of THF and stirred while thecrude free amino product is added dropwise at room temperature underargon. The mixture is gradually heated to 40° C. with stirring untilHPLC indicates the formation of the carboxamide linked product. Yieldedis 5-[2-{(4-chitosan methyl ether)benzoylamido}-4-methylvaleryloxy]-2-hexyl-hexadecanoic 1,3-lactone(about 15 grams).

EXAMPLE 24

[0245] A colorless power of (2S, 3S, 5S)3,5-dihydroxy-2-hexyl-hexadecanoic 1,3-lactone (6 g), produced as inExample 13 above (or as described on pages 11 and 12 of U.S. Pat. No.4,202,824) is dissolved in 500 mL of THF and 25 mL of anhydrous HCl towhich is added the acyl chloride derivative of the compound of Example21 (10 g). The reaction mixture is stirred and heated to reflux untilHPLC indicates that the esterification is essentially complete. Theorganic phase is separated from the aqueous phase and the solvent isevaporated. The resulting product is washed with warm hexane and withwater to provide funtionalized chitosan linked to the (2S, 3S, 5S)3,5-dihydroxy-2-hexyl-hexadecanoic 1,3-lactone as an ester derivative ofthe 5S hydroxy group (15 g).

[0246] In view of the above description it is believed that one ofordinary skill can practice the invention. The examples given above arenon-limiting in that one of ordinary skill in view of the above willreadily envision other permutations and variations on the inventionwithout departing from the principal concepts. Such permutations andvariations are also within the scope of the present invention.

What is claimed is:
 1. A process for making in at least 70% enantiomericpurity a (3S, 4S, 6S) oxetanone compound of the formula (I):

or a salt thereof wherein: R¹ and R³ are each independently a C₁ to C₁₈straight or branched alkyl hydrocarbon chain, and R² is hydrogen or analcohol protecting group R¹⁰, wherein R¹⁰ can be replaced by a hydrogenatom via ester hydrolysis or hydrogenation ether degradation, comprisingthe steps of: (a) selectively hydrogenating a composition comprising acompound which is a member selected from the group consisting of (6R)tetrahydro-2H-pyran-2-one compound of formula (II) and (6R)5,6-dihydro-2H-pyran-2,4-dione of formula (IIa):

wherein R⁵ is hydrogen or an alcohol protecting group, which can bereplaced by a hydrogen atom via hydrogenation, and R¹ and R³ are definedas in formula (I), by hydrogenating the compound of formula II with ahydrogenation catalyst selected from the group consisting of PtO₂, RaneyNichel and the like, and exchanging hydrogen atoms at the 3 and 4 ringpositions or oxidizing the 4-oxo group to provide a (3S, 4S, 6R)4-hydroxy-tetrahydro-2H-pyran-2-one compound of the formula (III):

wherein R¹ and R³ are defined as in formula (I); (b) re-protecting the4-hydroxy group of the compound of formula (II) produced in (a) with anether protecting group R⁶, which can be replaced by a hydrogen atom viaester hydrolysis or hydrogenation ether degradation, opening the lactonering and esterifying the resulting free acid group to provide a (2S, 3S,5R) [R⁷]2-[R³]-3-[R⁶⁻oxy]-5-[hydroxy, R¹]pentanoic acid ester compoundof the formula (IV):

wherein R¹ and R³ are defined as in formula (I), R⁶ is an alcoholprotecting group, which can be replaced by a hydrogen atom via esterhydrolysis or hydrogenation ether degradation, and R⁷ is an ester groupwhich can be removed by base or acid hydrolysis, or by hydrogenation;(c) inverting the chirality of the 5-hydroxy group of the compound offormula (IV) produced in step (b), wherein the inversion comprises astep which is a member selected from the group consisting of (iv) aMitsunobu reaction, (v) esterifying the 5-hydroxy group to a carboxylicacid ester such as the trichloroacetic acid ester, and the like, andhydrolyzing the resultant ester in a water ether solvent such as 3:1H₂O/dioxane, and (vi) esterifying the 5-hydroxy group to a sulfonic acidester, such as p-toluene sulfonic acid ester and the like, and reactingthe ester with an excess of an organic acid salt selected from the groupconsising of potassium acetate, sodium acetate, tetraethylammoniumacetate, and the like, to provide an ester exchange with the organicacid,  wherein the free inverted (5S) 5-hydroxy group of (i) and (ii) isesterified with a hydroxy protecting group R¹⁰ which can be which can bereplaced by a hydrogen atom via ester hydrolysis or hydrogenation etherdegradation, to provide a compound of the formula (V):

wherein R¹ and R³ are defined as in formula (I), R⁶ is an alcoholprotecting group, which can be replaced by a hydrogen atom via esterhydrolysis or hydrogenation ether degradation, R⁹ is an ester groupwhich can be removed by base or acid hydrolysis, or by hydrogenation,and R¹⁰ is an alcohol protecting group, which can be replaced by ahydrogen atom via ester hydrolysis or hydrogenation ether degradation,and wherein R¹⁰ is selectively removable with respect to the R⁶ alcoholprotecting group; and (d) selectively removing the R⁶ alcohol protectinggroup and R⁹ ester group of the compound of formula (V) produced in (c),and cyclizing the 3 position alcohol group with the 1 position acidgroup using a lactone cyclizing catalyst, such as benzene-sulphonylchloride, in a solvent such as pyridine at a temperature of about −10 to10° C. and optionally replacing the R¹⁰ alcohol protecting group offormula (V) with a hydrogen atom, to yield a (3S, 4S, 6S) oxetanonecompound of the formula (I):

or a salt thereof.
 2. A process according to claim 1, providing acompound of formula (I) wherein R¹ is undecyl, R³ is hexyl and R² ishydrogen, which is (2S, 3S, 5S) tetrahydroesterastin.
 3. A processaccording to claim 1, In another aspect the present invention relates tocoupling such compound of formula (I) to an acyl compound via an acid orbase esterification procedure without inversion of the 5S hydroxy group.4. A process according to claim 1, wherein the compound of formula (II)or (IIa) in step (a) is present at a ratio of from 90 to 100% withrespect to the corresponding (6S) enantiomer.
 5. A process according toclaim 3, wherein the compound of formula (II) or (IIa) in step (a) ispresent at a ratio greater than 97% with respect to the corresponding(6S) enantiomer.
 6. A process according to claim 1, further comprisingisolating a compound which is a member selected from the groupconsisting of the 6R compound of formula (IV), or its corresponding (6R,3RS, 4RS) racemate with an alcohol protected 3 hydroxyl group, from acompound which is a member selected from the 6S, 3R, 4R enantiomer withan alcohol protected 3 hydroxyl group corresponding to the compound informula (IV) and a compound which is the (6S, 3RS, 4RS) racematecorresponding to the compound of formula (IV), comprising a separationstep with is a member selected from the group consisting of: (i)selectively esterifying the 6-position hydroxyl group in the presence ofa lipase such as PS 30, porcine pancreas lipase, and the like, andseparating the ester from the alcohol, (ii) selectively hydrolyzing anester an ester of the 6-position hydroxyl group via a lipase such as PS30, porcine pancreas lipase, and the like, and separating the ester fromthe alcohol, (iii) forming a chiral salt with a chiral alcohol resolvingagent such as L-alaninol, D-alaninol, L-tartaric acid, D-tartaric acid,S-methylbenzyl-amine, D-methylbenzylamine in an appropriate solvent suchas methyl acetate, and the like, and separating the two enantiomers byre-cyrstallization; and (iv) other known chiral alcohol separatingprocedures, and removing any ester or protecting groups from the 6Rchiral hydroxyl group.
 7. A process according to claim 1, furthercomprising the steps of (a) inverting the 5S hydroxyl group of a (2R,3R, 5S or 2RS, 3RS, 5S) [R⁷]2-[R³]-3-[R⁶⁻oxy]-5-[hydroxy, R¹] pentanoicacid ester compound of the formula (VII):

wherein R¹, R³, R⁶ and R⁷ are defined as in formula IV; wherein theinversion comprises a step which is a member selected from the groupconsisting of (v) a Mitsunobu reaction, and freeing the hydroxyl group(vi) esterifying the 5-hydroxy group to a carboxylic acid ester such asthe trichloroacetic acid ester, and the like, and hydrolyzing theresultant ester in a water ether solvent such as 3:1 H₂O/dioxane to theinverted hydroxyl group, (vii) esterifying the 5-hydroxy group to asulfonic acid ester, such as p-toluene sulfonic acid ester and the like,and reacting the ester with an excess of an organic acid salt selectedfrom the group consising of potassium acetate, sodium acetate,tetraethylammonium acetate, and the like, to provide an ester exchangewith the organic acid, and hydrolyzing the organic acid ester to theinverted hydroxyl group, (viii) other known chiral alcohol inversionprocedures, (b) hydrolyzing the R⁷ ester group to provide the free acidcompound of the formula (VIII):

wherein R¹, R³ and R⁶ and R⁷ are defined as in formula (VII), and (c)cyclizing the inverted alcohol group of the compound of formula (VIII)with the 1 position acid group in the presence of a lactone cyclizingcatalyst such as tonuene-4-sulfonic acid monohydrate in an alcohol atabout 50-60° C. to provide a 6R tetrahydro-2H-pyran-2-one compound offormula (IX):

wherein R¹, R³, R⁶ and R⁷ are defined as in formula (VIII); and (d)selectively hydrogenating the (6R) tetrahydro-2H-pyran-2-one compound offormula (IX) with a hydrogenation catalyst selected from the groupconsisting of PtO₂, Raney Nichel and the like, and exchanging hydrogenatoms at the 3 and 4 ring positions to provide a (3S, 4S, 6R)4-hydroxy-tetrahydro-2H-pyran-2-one compound of the formula (IV):

wherein R¹ and R³ are defined as in formula (I).
 8. An intermediatecompound according to the formula:

wherein: R¹ and R³ are each independently a C₅ to C₁₈ straight orbranched alkyl chain which can be interrupted by 1 or 2 alkenyl doublebonds, and R² is hydrogen or an alcohol protecting group R¹⁰, whereinR¹⁰ can be replaced by a hydrogen atom via ester hydrolysis orhydrogenation ether degradation, and R¹⁰ is selectively removable withrespect to the R⁶ alcohol protecting group, or, a salt thereof.
 9. Acompound according to claim 8, wherein R¹ is undecyl and R³ is hexyl or,a salt thereof.